3CMZ

TEM-1 Class-A beta-lactamase L201P mutant apo structure

Summary for 3CMZ

• Entry DOI: 10.2210/pdb3cmz/pdb
• Related: 1JWP
• Descriptor: Beta-lactamase TEM, PHOSPHATE ION (3 entities in total)
• Functional Keywords: stabilization mutation, antibiotic resistance, hydrolase, plasmid, transposable element
• Biological source: Escherichia coli
• Total number of polymer chains: 1
• Total formula weight: 29020.92

Authors

Marciano, D.C.,Wang, X.,Wang, J.,Chen, Y.,Thomas, V.L.,Shoichet, B.K.,Palzkill, T. (deposition date: 2008-03-24, release date: 2008-11-25, Last modification date: 2024-10-30)

Primary citation

Marciano, D.C.,Pennington, J.M.,Wang, X.,Wang, J.,Chen, Y.,Thomas, V.L.,Shoichet, B.K.,Palzkill, T.
Genetic and structural characterization of an L201P global suppressor substitution in TEM-1 beta-lactamase
J.Mol.Biol., 384:151-164, 2008

PubMed Abstract: TEM-1 beta-lactamase confers bacterial resistance to penicillin antibiotics and has acquired mutations that permit the enzyme to hydrolyze extended-spectrum cephalosporins or to avoid inactivation by beta-lactamase inhibitors. However, many of these substitutions have been shown to reduce activity against penicillin antibiotics and/or result in loss of stability for the enzyme. In order to gain more information concerning the tradeoffs associated with active site substitutions, a genetic selection was used to find second site mutations that partially restore ampicillin resistance levels conferred by an R244A active site TEM-1 beta-lactamase mutant. An L201P substitution distant from the active site that enhanced ampicillin resistance levels and increased protein expression levels of the R244A TEM-1 mutant was identified. The L201P substitution also increases the ampicillin resistance levels and restores expression levels of a poorly expressed TEM-1 mutant with a core-disrupting substitution. In vitro thermal denaturation of purified protein indicated that the L201P mutation increases the T(m) value of the TEM-1 enzyme. The X-ray structure of the L201P TEM-1 mutant was determined to gain insight into the increase in enzyme stability. The proline substitution occurs at the N-terminus of an alpha-helix and may stabilize the enzyme by reducing the helix dipole, as well as by lowering the conformational entropy cost of folding due to the reduced number of conformations available in the unfolded state. Collectively, the data suggest that L201P promotes tolerance of some deleterious TEM-1 mutations by enhancing the protein stability of these mutants.

PubMed: 18822298
DOI: 10.1016/j.jmb.2008.09.009

Experimental method

X-RAY DIFFRACTION (1.92 Å)